- The overall goal of this research is to understand the regulation of extracellular matrix (ECM) production in human fibroblasts and its dysregulation in fibrotic diseases such as SSc. TGF-beta is one of the most potent inducers of extracellular matrix protein expression in fibroblasts and its presence in the lesions of scleroderma and other fibrotic diseases is well documented. There is also growing evidence that expansion of activated fibroblasts in fibrotic lesions may contribute to the disease progression. For the past several years, the principal investigator has focused on investigating the molecular mechanisms of fibroblast activation. The recent findings enable Dr. Trojanowska to propose the hypothesis that increased level of TGF-beta signaling through overexpression of TGF-beta type I and type II receptors is responsible for activation of SSc fibroblasts. Four specific aims are proposed to test this hypothesis as well as to gain more insight into TGF-beta signaling pathways in human fibroblasts. In specific aim 1, TGF-beta signaling will be blocked by overexpressing the dominant-negative TGF-beta receptor mutant and examining the phenotypic alterations of SSc fibroblasts that depend on autocrine TGF-beta signaling. In specific aim 2, the regulation of TGF-beta receptors by other cytokines will be explored. In specific aim 3, the investigators will map specific domains of the TGF-beta type I and II receptors involved in regulation of specific effects of TGF-beta on human fibroblasts (including regulation of expression of various extracellular matrix proteins, c-myc, and c-myb protooncogenes, and responses to selected growth factors). In specific aim 4, the cellular proteins that interact with TGF-beta receptors will begin to be characterized.